Various sequential methods are known for evaluation of probabilistic characteristics of hierarchical functional structures, as well as the systems for implementation of the above methods. The above methods use mathematical models of the structural elements of such structures, that include input and output parameters, as well as the mathematical models of dependencies between structural elements, that include input and output parameters. In this case, the evaluation of probabilistic characteristics is performed by implementing the process of executing simulation steps, the process which includes:                generating the random values of the variable input parameters of the mathematical models of structural elements, in each simulation step, according to the specified rules of their variability, and        determining the values of output parameters of the mathematical models of structural elements taking into account the output parameters of linked to the structural elements mathematical models of dependencies between structural elements, in each simulation step,        accumulating the simulation information about the values of output parameters of the mathematical models of the structural elements, and        evaluating the probabilistic characteristics of the structural elements upon completion of all simulation steps using the accumulated simulation information.        
The disadvantages of such methods and systems are:                difficulty to attain required accuracy of evaluation of probabilistic characteristics of hierarchical functional structures in the process of executing simulation steps, and        difficulty to simultaneously attain both integral and differential evaluation of probabilistic characteristics of such structures by the known methods.        